1. Field of the Invention
This invention relates to a whistle.
2. Description of the Related Art
Whistles are widely used by referees in various sporting events, for policing, guidance, and signaling where many people are gathered, as well as for guiding or training pets, and in numerous other fields as a simple tool for audio communication. A whistle must promptly convey sound to persons and animals in the environs, according to the various environments of use, and must excite their attention. For these reasons, a whistle-blower requires a whistle which can easily be held so as to enable prompt blowing as necessary. Moreover, listeners require a whistle emitting a sound with an easily discernible pitch and volume that can immediately be recognized. Whistles currently in use include pea-type whistles, having a pea which rotates within a resonance chamber, and pealess-type whistles, which have no pea. FIG. 9A shows a pea-type whistle 503, and FIG. 9B shows a pealess-type whistle 604.
A pea-type whistle 503 has as external dimensions a cylindrical body of diameter 19 to 20 mm×length of 17 to 20 mm, connected to a long, narrow rectangular parallelepiped-shape mouthpiece (length D 50 to 52 mm, height H 20 to 22 mm, width W 17 to 20 mm). Within this pea-type whistle 503 is a cylindrical resonance chamber of diameter 15 mm. This pea-type whistle 503 is normally blown while grasping the side faces of the cylindrical body.
On the other hand, the pealess-type whistle 604 has overall a long narrow box shape (with, as external dimensions, a length D of 51 to 54 mm, height H of 10 to 12 mm, and width W of 20 to 22 mm). This pealess-type whistle 604 is blown while grasping the side walls with the fingers.
In addition, the following inventions, adding improvements to the above general types of whistle, have been disclosed.
Japanese Patent Application Laid-open No. 2002-108345 discloses a whistle provided with a wall type deflector named air flow converter at the mouthpiece-side end of the orifice (the posterior end of the orifice), or at the mouthpiece-side end of the orifice and on the right and left of the orifice. In this whistle, the deflector changes the flow of air, to increase the higher harmonics. Specifically, by means of the deflector a negative-pressure region occurs on the lower side of this deflector, and the airflow amplitude is made large, to increase the high harmonics.
In U.S. Pat. No. 5,329,872, an all-weather type whistle is disclosed. This whistle has as an object use in water or in rainy weather. One end of the orifice upper portion of this whistle is covered by a semicircular cowling extending from the mouthpiece upper plate. When the orifice is thus surrounded by the cowling, air accumulates in the vicinity of the orifice in water, and so the passage of water through the orifice to enter into the resonance chamber is prevented. Moreover, this cowling prevents the ingress of rain. Further, the sound-emitting opening of this whistle is directed forward or downward.
Japanese Utility Model Laid-open No. S39-21231 discloses a volleyball referee whistle. In volleyball, in order to accurately observe play at the net, a referee sits on a referee's stand at a height of approximately 2 m, installed at a right angle to the net, to judge play. For this reason, whistle sounds must be emitted toward the players below. Hence the mouthpiece of this whistle is flexed downward in a circular arc, such that when held in the mouth the sound-emitting opening (orifice) is directed forward.
A whistle is a tool which utilizes a resonance phenomenon for blowing. Sound waves generated in the resonance phenomenon are the fundamental resonance frequency sound wave, and harmonic frequency sound waves at multiples of the fundamental resonance frequency. Hence the higher the fundamental resonance frequency, the higher the harmonic frequencies as well, and overall the sound wave generated is a higher-frequency sound. The fundamental resonance frequency is determined by the size of the resonance chamber. Specifically, the fundamental resonance frequency is inversely proportional to the size of the resonance chamber, and falls as the resonance chamber is made larger.
Based on the above-described dimensions, the fundamental resonance frequency of whistles of the prior art is from 3.3 to 3.5 kHz for pea-type whistles, and from 3.5 to 3.7 kHz for pealess-type whistles. Sounds at these frequencies, and sounds having harmonics based on these frequencies, are shrill and unpleasant sounds, and so improvement has been sought.
In response, increasing the size of the resonance chamber to lower the fundamental resonance frequency is conceivable. However, merely increasing the size of the resonance chamber fails to satisfy the need for a small and lightweight whistle, and is poor in terms of design as well. For example, in the case of the pea-type whistle 503 of the prior art described above, the cylinder diameter is increased to 35 to 40 mm, so that the whistle becomes large. Moreover, the whistles of the prior art give rise to the following problem.
In the whistles 503 and 604 of the prior art shown in FIG. 9A and FIG. 9B, air blown in from the air passageways 528 and 628 collides with the edges of the orifices 524, 624, and as a result sound waves are generated. A portion of the sound waves is selectively amplified by the resonance chamber 551, 651 through the resonance effect. The sound waves generated are immediately emitted to the outside from the orifices 524, 624. That is, in the whistles 503, 604 of the prior art, the orifices 524, 624 also serve as sound-emitting openings. These orifices (sound-emitting openings) 524, 624 are directed upward. As a result, as indicated by the arrows in FIG. 9A and FIG. 9B, the sound waves are emitted in radial form from the orifices 524, 624. The distance from the mouth to the ears for humans is generally approximately 15 cm. Hence sound waves leaving the orifices 524, 624 reach the ears 52 of the whistle-blower directly. As a result, in the case of the whistles of the prior art the whistle-blower must listen to the sound at high volume, normally approximately 120 dB/m, and at an unpleasant high frequency. This entails the possibility of affliction of the whistle-blower with a hearing disorder, or of ringing of the ears, or other problems. Even when such problems do not occur, sports referees and similar who blow whistles for extended periods of time may then not be able to hear sounds for some time thereafter. The lengths heights of the orifices 524, 624 in the sound emitting direction are stipulated by the thickness of the casing.
The whistle-blower normally holds the pea-type whistle 503 grasping the side faces of the cylindrical body. However, due to the circular shape of the side faces of the cylindrical body, the grasping angle is not readily determined. Further, the area to hold the whistle is insufficient. Hence there are problems such as failure of the whistle-blower to hold the whistle, or delays in blowing the whistle. The pealess-type whistle 604 also has a side face height which is only approximately half the size of the fingertips of an adult, and so has the problem of being extremely hard to hold.
To address these problems, in U.S. Pat. No. 5,086,726, a whistle is proposed which has side faces in a mandolin shape, of height 21 mm. If the overall dimensions are made large, the above problem can be resolved, but this fails to meet the need for a small and lightweight whistle.
In the case of the whistle of Japanese Patent Application Laid-open No. 2002-108345, the orifice also serves as a sound-emitting opening, and the shrill high-harmonic sound generated in the resonance chamber exists unmodified through the orifice. Consequently sounds generated by the whistle have amplified shrill high-frequency sounds and high harmonics, that is, high frequencies, and the sound is unpleasant. Also, because the orifice is directed upwards or downwards, high-frequency sound enters the ears of the whistle-blower directly. As a result, there is the problem that the whistle-blower may suffer a hearing disorder, or may feel ringing of the ears.
In the case of the whistle of U.S. Pat. No. 5,329,872, a semicircular cowling completely covers the top of the orifice. Consequently sound waves flowing out from the orifice all collide with the cowling, changing the sound waves to an acute angle in the propagation direction as sound waves are emitted from the sound-emitting opening. This change in propagation is 90° or 180° downward. In such a structure, the following problems occur.
First, due to the collision with the cowling and the change to an acute angle of the propagation direction, the energy loss of the sound waves is large, and the sound volume is greatly reduced. Second, because the sound-emitting opening is directed downward or forward, when using the whistle while grasping the side faces with the fingertips with the hand held below, the fingers and hand cover the sound-emitting opening, sound emission is impeded, and the sound volume is greatly reduced. Further, because the height of the cowling is high in order to prevent intrusion of water and rain, the cowling absorbs sound so that the sound volume is reduced, and so there is the problem that the original role of a whistle, which is to convey sound to distant listeners, is not achieved.
In the case of the whistle of Japanese Utility Model Laid-open No. S39-21231 also, grasping is difficult due to the narrow cylindrical shape, and moreover there is the problem that the hand blocks the sound-emitting opening, causing the sound volume to be reduced. Also, because the orifice also serves as the sound-emitting opening, there are the same problems as with other whistles of the prior art.